The vast majority of current Internet usage consists of content being disseminated from a source to a number of users. To meet growing demands, service providers (e.g., Google) are ushered to invest in large data centers with hundreds of thousands machines distributed across different geographic regions. Similarly, network providers have been increasing network capacity by deploying a large number of high-speed routers and fiber cables. Networking devices such as servers, core/edge routers, and access devices involved in this large scale content delivery consume significant energy; for instance, the U.S. Environmental Protection Agency (EPA) estimates that data centers could consume 100 billion kilowatt hours at a cost of $7.4 billion per year by 2011.
Given this large consumption of energy, it would be desirable to focus on energy efficiency of modern high-speed routers that play a significant role in that content delivery chain. A modern router is typically equipped with hundreds of network processors for fast processing of data plane tasks (e.g., routing, packet classification, encryption, QoS, etc). Since the energy consumption of those network processors (NPs) dominates that of packet transport over the wires, one way of reducing energy consumption is to dynamically provision network processors on the basis of time varying traffic volume demands. For instance, if the utilization of a router is 70% to route a current volume of traffic, the router configures its processing rate as 70% of its peak rate. To this end, modern network processors employ Dynamic Voltage Scaling (DVS) that allows NPs to slow down their operating frequency (or rate) and lower their operating voltage to save energy.
However, current DVS techniques do not take into account QoS commitments of the traffic being routed, which commitments if not met can affect a network providers' revenues. Therefore, it would be desirable to have a means of achieving greater energy efficiency in network routers while at the same time respecting QoS commitments, such as service level agreements (SLAs).